• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.15 no.5
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• pp.299-307
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• 2022

Harmony Search (HS) is a relatively recently developed meta-heuristic optimization algorithm, and various studies have been conducted on it. HS is based on the musician's improvisational performance, and the objective variables play the role of the instrument. However, each instrument is given only a sound range, and there is no concept of a scale that can be said to be the basis of music. In this study, the performance of the algorithm is improved by introducing a scale to the existing HS and quantizing the bandwidth. The introduced scale was applied to HM initialization instead of the existing method that was randomly initialized in the sound band. The quantization step can be set arbitrarily, and through this, a relatively large bandwidth is used at the beginning of the algorithm to improve the exploration of the algorithm, and a small bandwidth is used to improve the exploitation in the second half. Through the introduction of scale and bandwidth quantization, it was possible to reduce the algorithm performance deviation due to the initial value and improve the algorithm convergence speed and success rate compared to the existing HS. The results of this study were confirmed by comparing examples of optimization values for various functions with the conventional method. Specific comparative values were described in the simulation.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.3
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• pp.249-255
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• 2017

The finger vein recognition technology is a method to acquire a finger vein image by illuminating infrared light to the finger and to authenticate a person through processes such as feature extraction and matching. In order to recognize a finger vein, a 2D mask-based two-dimensional convolution method can be used to detect a finger edge but it takes too much computation time when it is applied to a low cost micro-processor or micro-controller. To solve this problem and improve the recognition rate, this study proposed an extraction method for the region of interest based on virtual core points and moving average filtering based on the threshold and absolute value of difference between pixels without using 2D convolution and 2D masks. To evaluate the performance of the proposed method, 600 finger vein images were used to compare the edge extraction speed and accuracy of ROI extraction between the proposed method and existing methods. The comparison result showed that a processing speed of the proposed method was at least twice faster than those of the existing methods and the accuracy of ROI extraction was 6% higher than those of the existing methods. From the results, the proposed method is expected to have high processing speed and high recognition rate when it is applied to inexpensive microprocessors.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.39 no.3
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• pp.88-98
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• 2002

The multilayer perceptron (MLP) has several advantages against other pattern recognition methods, and is expected to be used as the learning and recognizing speakers of speaker verification system. But because of the low learning speed of the error backpropagation (EBP) algorithm that is used for the MLP learning, the MLP learning requires considerable time. Because the speaker verification system must provide verification services just after a speaker's enrollment, it is required to solve the problem. So, this paper tries to make short of time required to enroll speakers with the MLP based speaker verification system, using the method of improving the EBP learning speed and the method of reducing background speakers which adopts the cohort speakers method from the existing speaker verification.

• Journal of Advanced Navigation Technology
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• v.24 no.3
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• pp.198-204
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• 2020

This paper designs a electromagnetic-log (EM-Log) aided navigation filter for maritime environment without global navigation satellite system (GNSS). When navigation is performed for a long time, Inertial navigation system (INS)'s error gradually diverges. Therefore, an integrated navigation method is used to solve this problem. EM-Log sensor measures the velocity of the vehicle. However, since the measured velocity from EM-Log contains the speed of the sea current, the aided navigation filter is required to estimate the sea current. This paper proposes a single model filter and interacting multiple (IMM) model filter methods to estimate the sea current and analyzes the influence of the sea current model on the filter. The performance of the designed aided navigation filter is verified using a simulation and the improvement rate of the filter compared to the pure navigation is analyzed. The performance of single model filter is improved when the sea current model is correct. However, when the sea current model is incorrect, the performance decreases. On the other hands, IMM model filter methods show the stable performance compared to the single model.

• Journal of Digital Contents Society
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• v.2 no.2
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• pp.179-189
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• 2001

This paper aims at faster processing and retrieval in fingerprint identification systems by reducing the amount of preprocessing and the size of the feature vector. The distribution of fingerprint directions is a set of local directions of ridges and furrows in small overlapped blocks in a fingerprint image. It is extracted initially as a set of 8-direction components through the Gabor filter bank. The discontinuous distribution of directions is smoothed to a continuous one and visualized as a direction image. Then the center of the distribution is selected as a reference point. A feature vector is composed of 192 sine values of the ridge angles at 32-equiangular positions with 6 different distances from the reference point in the direction image. Experiments show that the proposed algorithm performs the same level of correct identification as a conventional algorithm does, while speeding up the overall processing significantly by reducing the length of the feature vector.

• Journal of KIISE:Software and Applications
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• v.37 no.11
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• pp.851-858
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• 2010

Most mobile devices use a NAND flash memory as their secondary memory. A compressed code of the firmware is stored in the NAND flash memory of mobile devices in order to reduce the size and the loading time of the firmware from the NAND flash memory to a main memory. In order to use a demand paging properly, a compressed code should be decompressed very quickly. The thesis introduces a new dictionary based compression algorithm for the fast decompression. The introduced compression algorithm uses a different method with the current LZ method by storing the "exclusive or" value of the two instructions when the instruction for compression is not equal to the referenced instruction. Therefore, the thesis introduces a new compression format that minimizes the bit operation in order to improve the speed of decompression. The experimental results show that the decoding time is reduced up to 5 times and the compression ratio is improved up to 4% compared to the zlib. Moreover, the proposed compression method with the fast decoding time leads to 10-20% speed up of booting time compared to the booting time of the uncompressed method.

• Journal of Korean Society of Transportation
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• v.35 no.4
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• pp.278-291
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• 2017

Effective installation and operations of traffic safety signs in the advance warning area is of considerable interest for safer traffic management at freeway work zones. This study evaluated the feasibility of traffic safety sign installation based on a driving simulation experiment to take drivers' responsive characteristics into consideration. Both the compliance rate for speed limit and a lane-changing safety index were used for evaluating a set of driving simulation scenarios. It was identified that providing speed limit signs to reduce speed in advance and afterward guiding lane-changing could lead to safer maneuvering of vehicles entering work zones. The outcomes of this study are expected to be useful for revising freeway work zone management policies toward crash prevention.

• Membrane Journal
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• v.24 no.6
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• pp.453-462
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• 2014

Thin film composite (TFC) polyamide (PA) membranes were prepared on polyester (PET) nonwoven reinforced polysulfone supports for forward osmosis (FO) processes. PSF (polysulfone) supports were prepared via the phase inversion process from PSF casting solutions in dimethyl formamide (DMF) solvents (19 wt%) by using a PET nonwoven (thickness of $100{\mu}m$) as a mechanical reinforcing material for reverse osmosis (RO) membrane. The PSF support from 19 wt% of DMF/PSF casting solution showed sponge-like morphology and asymmetric internal structure. To reduce the internal concentration polarization in FO operation, thin ($20{\mu}m$ of thickness) nonwoven-supported PSF supports were prepared by using PSF/DMF casting solution (9~19 wt%). A desirable support structure with a highly porous sponge-like morphology were achieved from the thin nonwoven-supported PSF layer prepared with 9~12 wt% casting solution. A crosslinked aromatic polyamide layer was fabricated on top of each support to form a TFC PA membrane. The tested sample from 12 wt% of DMF/PSF casting solution presented outstanding FO performance, almost 5.5 times higher water flux (24.3 LMH) with low reverse salt flux (RDF, 1.5 GMH) compared to a thick nonwoven rainforced membrane (4.5 LMH of flux and 3.47 GMH of RSF). By reducing the thickness of the nonwoven and optimizing PSF concentration of casting solution, the morphology of the prepared membranes were changed from a dense structure to a porous sponge structure in the boundary area between nonwoven and PET support layer.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.2
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• pp.397-407
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• 2017

This study investigated current status of rest area for drowsy drivers on the highways and drew the related issues to define specifications and design criteria regarding expressway rest area for drowsy drivers on the highways. Based on the investigation result, geometric structure specifications and improvement plans are suggested. The entry part of a rest area for drowsy drivers on the highways was divided into deceleration transition section, deceleration lane and entry connection road while the exit part was divided into exit connection road, acceleration lane and acceleration transition section. The optimum length was estimated by considering the main lane vehicle traveling speed, traveling speed at the beginning/end point of entry/exit connection roads, deceleration and acceleration. In addition, reasonable design criteria were suggested by dividing the parking section of rest area for drowsy drivers according to parking style and cross-section composition, and length of parking space and then considering the ratio of vehicles using rest area for drowsy drivers, the ratio of heavy vehicles, and the design speed within a rest area for drowsy drivers. It is believed that the suggested design criteria on rest area for drowsy drivers on the highways can be utilized in the future planning and maintenance of rest area for drowsy drivers. Additionally, the defined criteria on installing rest area for drowsy drivers on the highways will prevent traffic accidents in resting facilities and highways as well as improve usage and safety of them.

• Food Science and Preservation
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• v.24 no.1
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• pp.60-67
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• 2017

In this study, we tried to establish the best method for fresh blueberry beverage production using enzyme treatment as well as low temperature extraction. During extraction of physiologically functional materials, we used low temperature to prevent nutritional loss by heat. In addition, we investigated optimal blueberry extraction conditions using various enzyme treatments (cellulase, pectinase, cellulase:pectinase (1:1) mixture) to increase extraction efficiency and reduce turbidity. A variety and ratio of enzymes, extraction temperature, extraction time, and shaking speed were considered for the best extraction efficiency rate. We observed high extraction efficiency rates of 85.72-86.55% and 87.06-87.93%, respectively, upon cellulase or pectinase treatment. In addition, a mixture of cellulase:pectinase (1:1) showed an extraction efficiency rate of 86.84-88.14%. The best extraction efficiency rate was observed when crude blueberry was treated at $45^{\circ}C$ (87.91%), for 3 h (87.88%), in a 90 rpm shaker (89.19%). Sugar content and acidity of blueberry extract were not affected by the various treatments. However, total phenolic compounds were detected upon pectinase treatment (18.62 mg/g). Only fructose and glucose as free sugars were found in all samples regardless of treatments and extraction conditions.